Graininess, sharpness and color reproduction are generally recognized as the three major factors which affect image quality of color photography. With the recent marked improvement in image quality of silver halide color photographic light-sensitive materials, the achievements have been almost satisfactory in some markets such as the market for light-sensitive materials for professional use, in which printing is conducted using large formats under strict process management with high precision.
However, in the color light-sensitive materials for ordinary amateurs, image quality remains unsatisfactory when small formats are preferred for operational facility or when high sensitivity light-sensitive materials are selected to lessen photographic load on the user.
Also, in the printing process in said amateur market, basic quality management has been implemented to increase productivity and profitability; uniformity in silver halide color photographic light-sensitive material, including storage stability, immediately affects print quality. It is therefore necessary not only to further improve image quality but also to meet the market requirement of uniform and stable image quality by further improvement.
For improving graininess, a way to quality improvement, reducing the silver halide grain volume is a well-known means, but this is undesirable because it results in sensitivity degradation. Increasing the sensitivity of light-sensitive material grains while retaining the same volume can therefore be related to graininess improving.
Generally, a color light-sensitive material comprises a blue, green and red sensitive units of spectrally sensitized silver halide emulsion. Spectral sensitization dyes tend to significantly affect the sensitivity and color reproducibility of silver halide emulsion and the storage stability of light-sensitive material.
For this reason, a large number of means for sensitizing dyes for color photographic emulsion have been known, including those disclosed in Japanese Patent Examined Publication Nos. 6209/1974, 1569/1980 and 39460/1981 and Japanese Patent Publication Open to Public Inspection (hereinafter referred to as Japanese Patent O.P.I. Publication) Nos. 11419/1974 and 12541/1985, in which the spectral sensitivity distribution is confined within a particular range to prevent color change among picture taking light sources. Moreover, the combination of dyes used in the red- and green-sensitive layers has recently been specified to improve the color reproducibility and storage stability of silver halide color photographic light-sensitive material, as disclosed in Japanese Patent O.P.I. Publication No. 239247/1991.
However, all these conventional methods are accompanied by undesirable dye staining after development. This is a secondary adverse factor of color reproduction deterioration from the viewpoint of suitability to automatic printer which occurs in addition to the primary problem of color reproducibility change.
Moreover, these methods are not sufficient to meet the two requirements of high sensitivity and good color reproduction; there has been a strong demand for the development of a new technology.